A generic simulation model for evaluating concurrency control protocols in native XML database systems

In this paper we propose a generic simulation model, named XSM, with which researchers can construct standard platforms and evaluate their proposed concurrency control protocols for native XDBMSs. The system environment, the performance metrics, and the protocol rules of various types of XML protocols are all considered by the model. To facilitate the implementation of XSM, the state diagrams, the sequence diagrams, the component diagram, and the class diagram of XSM are depicted using UML 2.0 notations. We also show a simulation platform constructed from XSM to fairly and comprehensively evaluate the performance of various XML protocols.     

Applying web-enabled self-regulated learning and problem-based learning with initiation to involve low-achieving students in learning

Vocational degree earners represent a major portion of the work force in Taiwan. However, vocational education in Taiwan is highly competitive in that it must attract sufficient student enrollment in an environment with a rapidly increasing number of schools. In this context, many vocational students tend to have lower levels of academic achievement. Under such constraints but moving toward more practical orientation, the authors conducted a quasi-experiment to examine the effects of applying web-based self-regulated learning (SRL), web-based problem-based learning (PBL) with initiation, and their combination to help these low-achieving students be involved positively in their learning. Four classes in successive years, with a total of 177 third-year students, were divided into 2 (SRL vs. non-SRL) × 2 (PBL with initiation vs. PBL without initiation) experimental groups. Results were generally positive. The authors further discuss the implications for schools, particularly vocational schools, and for scholars and teachers concerned about e-learning.     

Optimal placement of line switches for distribution automation systems using immune algorithm

To enhance the cost effectiveness of the distribution automation system (DAS), this paper proposes the immune algorithm (IA) to derive the optimal placement of switching devices by minimizing the total cost of customer service outage and investment cost of line switches. The reliability index of each service zone defined by the boundary switches is derived to solve the expected energy not served due to fault contingency, and the customer interruption cost is then determined according to the customer type and power consumption within the service zone. To demonstrate the effectiveness of proposed IA methodology to solve the optimal placement of line switches, a practical distribution system of Taiwan Power Company (Taipower) is selected for computer simulation to explore the cost benefit of line switch placement for DAS.     

Magnetic microparticle-polydimethylsiloxane composite for reversible microchannel bonding

In this study, an iron oxide magnetic microparticles and poly(dimethylsiloxane) (MMPs-PDMS) composite material was employed to demonstrate a simple high-strength reversible magnetic bonding method. This paper presents the casting of opaque-view (where optical inspection through the microchannels was impossible) and clear-view (where optical inspection through the microchannel was possible) MMPs-PDMS. The influence of the microchannel geometries on the casting of the opaque-view casting was limited, which is similar to standard PDMS casting. Clear-view casting performance was highly associated with the microchannel geometries. The effects of the microchannel layout and the gap between the PDMS cover layer and the micromold substrate were thoroughly investigated. Compared with the native PDMS bonding strength of 31 kPa, the MMPs-PDMS magnetic bonding experiments showed that the thin PDMS film with an MMPs-PDMS layer effectively reduced the surface roughness and enhanced MMPs-PDMS reversible magnetic bonding strength. A thin PDMS film-coated opaque-view MMPs-PDMS device exhibited the greatest bonding strength of 110 kPa, and a clear-view MMPs-PDMS device with a thin PDMS film attained a magnetic bonding strength of 81 kPa.     

Effects of barium dissolution on dispersing aqueous barium titanate suspensions

Dissolution of barium ion and its effect on dispersion behavior of aqueous barium titanate suspensions at various pH values have been investigated. The amount of leached barium ion decreases with increasing pH value. The dissolution of barium ion also causes an increase in pH value of suspension, but the change decreases with increasing initial pH value. The iso-electric point (IEP) of leached barium titanate powder increases with increasing leaching pH value and solid loading as well. The dissolution of barium ion enhances the colloidal stability of aqueous barium titanate suspension, in agreement with zeta potential measurement.     

Automatic inspection of the width and gap of etching transistors in TFT-LCD panels using sub-pixel accuracy estimation

In this paper, the width and gap of etching transistors in TFT-LCD panels were measured using sub-pixel accuracy estimation, and the accuracy was tested in a noisy environment. The concept of line width measurement was introduced in terms of line distance and defect measurement based on the low and high spatial frequency distribution change of TFT-LCD panel image. Some patterns do not need to have the line width and distance measured, while others have different measurement requirements. The conductor border of a pattern is normally an area with a flat change of grey scale, but we are still able to find an accurate measurement with the proposed method. In the TFT-LCD testing pattern, there are circular etching structures, and for measurement we focus on the position of the center of the circle and the size of the radius. This method can be used quickly and accurately for measuring the TFT short, ITO open, marking, spot particle or scratching on the panel caused by over etching.     

Applying online externally-facilitated regulated learning and computational thinking to improve students’ learning

This study aims to explore, via quasi-experiments, the effects of online externally-facilitated regulated learning (ERL) and computational thinking (CT) on improving students’ computing skills in a blended learning environment. Four classes in a one-semester course entitled ‘Applied Information Technology: Data Processing’ were the samples for this research. The first class (C1, ERL&CT group) simultaneously received the interventions regarding online ERL and CT, the second class (C2, CT group) received the intervention regarding online CT, and the third class (C3, ERL group) received the intervention regarding online CT, while the last group (C4, control group) received a traditional teaching method, although teaching was also conducted in a blended computing class. Students in ERL&CT group and CT group came from the Department of Finance, while the ERL group and control group came from the Department of Law at a comprehensive university. According to the posttest analysis, the results indicate that students who received the intervention of online ERL had statistically better development of computing skills for using Excel by semester-end than those without. In addition, this study also reveals that the application of online CT alone could be helpful in students’ development of computing skills. Furthermore, the results indicate that students’ computing skills could be improved under the condition of simultaneously applying ERL and CT. Based on the findings of this study, the authors present implications for online teachers and educators, particularly for those teaching computing courses.     

Effects of metal layer morphology to silicon nanostructure formation in metal-assisted etching

This study presents a rapid and simple approach for creating silicon nanostructures using metal-assisted etching. The thickness of the metal layer was found to be a key process parameter affecting the surface morphology of silicon nanostructures. Au and Ag layers with a thickness of 3 nm, 5 nm, and 10 nm were used to study the effects of metal catalyst thickness on silicon nanostructure morphology. The experimental results show that the surface morphology of metal has a significant influence on the silicon nanostructure morphology, such that the silicon nanostructures transform from porous silicon surfaces into filament nanostructures or silicon nanowire with increasing thicknesses of both the Au and Ag metal layers.     

Generalized finite difference method for solving two-dimensional non-linear obstacle problems

In this study, the obstacle problems, also known as the non-linear free boundary problems, are analyzed by the generalized finite difference method (GFDM) and the fictitious time integration method (FTIM). The GFDM, one of the newly-developed domain-type meshless methods, is adopted in this study for spatial discretization. Using GFDM can avoid the tasks of mesh generation and numerical integration and also retain the high accuracy of numerical results. The obstacle problem is extremely difficult to be solved by any numerical scheme, since two different types of governing equations are imposed on the computational domain and the interfaces between these two regions are unknown. The obstacle problem will be mathematically formulated as the non-linear complementarity problems (NCPs) and then a system of non-linear algebraic equations (NAEs) will be formed by using the GFDM and the Fischer–Burmeister NCP-function. Then, the FTIM, a simple and powerful solver for NAEs, is used solve the system of NAEs. The FTIM is free from calculating the inverse of Jacobian matrix. Three numerical examples are provided to validate the simplicity and accuracy of the proposed meshless numerical scheme for dealing with two-dimensional obstacle problems.